Weaning piglets need diets built around highly digestible ingredients, particularly milk-based products and quality protein sources, that bridge the gap between sow’s milk and a grain-based grower diet. The transition is one of the most stressful periods in a pig’s life, and getting the feed right during the first few weeks post-weaning has an outsized effect on lifetime performance. A piglet weaned at 28 days with a normal body weight of around 8 to 9 kg is in good shape to handle the switch, while lighter piglets (closer to 5 kg) need extra nutritional support to catch up.
Why Weaning Diets Differ From Grower Diets
A piglet’s digestive system at weaning is still immature. The stomach produces insufficient hydrochloric acid, which means it can’t activate protein-digesting enzymes efficiently or kill harmful bacteria the way an older pig’s gut can. At the same time, the piglet is abruptly losing the highly digestible, fat-rich nutrition of sow’s milk and facing a completely unfamiliar solid feed. This combination of gut immaturity and dietary stress is what makes post-weaning diarrhea (scours) so common and so costly.
The goal of a weaning diet is to provide nutrients in forms the immature gut can actually absorb while encouraging the piglet to eat as much as possible. That means relying heavily on milk products, easily digested protein sources, and feed additives that support gut health, then gradually shifting toward cheaper, plant-based ingredients as the digestive system matures over the following weeks.
Start With Creep Feed Before Weaning
Introducing solid feed while piglets are still nursing, known as creep feeding, gives their gut a head start on adapting. Creep feed is typically offered starting around 5 to 7 days of age and continues until weaning at 21 to 28 days. The earlier piglets learn to eat solid feed, the less dramatic the transition at weaning.
The form and composition of creep feed matters more than most producers realize. In a trial comparing different creep feeds, piglets given a liquid milk replacer consumed significantly more feed and had greater body weight at weaning (6.3 kg) compared to those given a pelleted commercial creep feed (6.0 kg) or no creep feed at all (5.9 kg). Liquid or powder-based milk products are more palatable and more closely mimic sow’s milk, which drives early intake. A pelleted creep feed based on corn and fishmeal still works, but piglets are slower to take to it.
Even small differences in weaning weight compound quickly. Piglets that eat creep feed transition to nursery diets faster and experience less of the growth slump that typically follows weaning.
Lactose Is the Most Important Early Ingredient
Lactose, the sugar in milk, is the single most critical ingredient in the first week after weaning. A meta-analysis of multiple trials found that diets should contain about 20% lactose during the first 7 days post-weaning and 15% from days 7 to 14. After two weeks, piglets can handle diets with little or no lactose as their ability to digest plant-based starches improves.
Dried whey is the most common and cost-effective source of lactose in piglet diets. A typical early weaning diet (for piglets under 11 pounds) includes around 500 pounds of spray-dried whey per ton of feed, making it the single largest ingredient after corn. Whey protein concentrate is another option that delivers both lactose and highly digestible protein. These inclusion levels are high, and they’re expensive, but cutting lactose too early reliably reduces feed intake and triggers digestive problems.
Choosing the Right Protein Sources
Piglets in the 5 to 7 kg range need diets with 24 to 26% crude protein, dropping to 22 to 24% as they reach 7 to 11 kg, and 21 to 23% from 11 to 25 kg. Total lysine, the most important amino acid for growth, should be around 1.70% for the smallest piglets, 1.53% for piglets in the 7 to 11 kg range, and 1.40% from 11 to 25 kg.
Not all protein sources are equal for young pigs. Animal-based proteins are generally more digestible than plant proteins because plant cell walls and fiber can block digestive enzymes from reaching the nutrients inside. The most common protein sources in early weaning diets include spray-dried animal plasma, fishmeal, spray-dried blood meal, and soybean meal or further-processed soy products. These are typically used in combination rather than relying on any single source.
Spray-dried animal plasma deserves special mention. It contains antibodies that support gut health during the vulnerable post-weaning period, and it’s one of the most palatable protein sources available. Fishmeal (often menhaden fishmeal) is another staple, included at roughly 120 pounds per ton in early weaning diets. It provides highly digestible protein and essential amino acids.
Soybean meal is inexpensive and widely available, but it contains compounds that can irritate the immature piglet gut and trigger immune responses. Processed soy products with these compounds removed are safer for very young pigs. As piglets grow past 15 kg, standard soybean meal becomes a perfectly adequate primary protein source.
Phase Feeding: Changing Diets as Piglets Grow
Weaning diets aren’t one-size-fits-all. The standard approach is phase feeding, where the diet composition changes every one to two weeks to match the piglet’s developing digestive capacity.
- Phase 1 (weaning to about 5 kg, or 11 lbs): The most complex and expensive diet. Heavy on dried whey (20% lactose), spray-dried plasma, fishmeal, and minimal soybean meal. Multiple protein sources are combined to meet the very high amino acid requirements.
- Phase 2 (roughly 5 to 7 kg, or 11 to 15 lbs): Lactose drops to around 15%. Plasma can be reduced or removed, while fishmeal and processed soy products increase. Crude protein stays in the 22 to 24% range.
- Phase 3 (7 to 11 kg, or 15 to 25 lbs): Lactose is no longer necessary. The diet shifts toward a simpler corn-soybean meal base. Fishmeal can be reduced. Crude protein targets 21 to 23%.
The exact transition points depend on your weaning age, piglet weights, and budget. The principle is always the same: start with the most digestible, milk-heavy diet you can afford and simplify as the gut matures.
Feed Additives That Prevent Scours
Post-weaning diarrhea is driven largely by the piglet’s inability to maintain a low enough stomach pH to kill harmful bacteria. Organic acids added to the feed help fill this gap. They lower the pH of the stomach contents, increase the activity of protein-digesting enzymes, and directly inhibit pathogens by penetrating bacterial cell walls and disrupting their internal chemistry.
Blends of organic acids, particularly those containing formic acid, have proven effective. In a controlled trial where piglets were deliberately infected with a common diarrhea-causing strain of E. coli, organic acid supplementation at 0.3% of the diet reduced diarrhea frequency from about 39% in untreated pigs to roughly 30%. The acids also reduced the shedding of harmful bacteria in feces. Using a blend of acids with different chemical properties provides broader coverage throughout the digestive tract, since different acids are active at different pH levels.
Other common additives include zinc oxide (widely used but increasingly restricted in some countries due to environmental concerns), probiotics, and prebiotics. Organic acids are among the most consistently supported by research and are a practical first choice for most operations.
Water and Feeder Management
Fresh water is easy to overlook but directly limits feed intake. A simple rule of thumb: piglets drink roughly 3 liters of water for every kilogram of feed they consume, plus a small baseline amount. If water access is limited, feed intake drops immediately. Nipple drinkers should be positioned at shoulder height and checked daily to ensure they’re flowing properly. Providing a shallow water bowl alongside nipple drinkers in the first few days after weaning helps piglets that haven’t yet learned to use nipples.
Feeder space also matters more than many producers assume. Traditional recommendations suggest 4 to 11 piglets per feeder space when using dry feeders without dividers. Research from the University of Minnesota found that providing more generous feeder access (about 1.6 pigs per feeder space rather than 4) improved growth in slower-growing pigs. If you have lightweight or stressed piglets, extra feeder space is a simple intervention that costs little but can meaningfully improve intake during the critical first weeks.
For the first two to three days after weaning, consider offering small amounts of feed frequently on a flat tray or mat in addition to the regular feeder. This mimics the way piglets learned to eat creep feed and encourages the tentative eaters to start consuming solid feed sooner.
Putting It All Together
The most practical summary for feeding weaning piglets comes down to a few priorities. Keep lactose high (20%) in the first week and taper it over two weeks. Use multiple highly digestible protein sources, especially spray-dried plasma and fishmeal, in the earliest diets. Transition toward corn-soybean meal as piglets pass 7 to 11 kg. Add organic acids to support gut pH and reduce scours risk. Ensure unlimited access to clean water and generous feeder space, particularly for lighter piglets. And if possible, get piglets eating creep feed before weaning so their guts are already adapting when the sow’s milk disappears.